Dual-control device



T. A. PEEBLES DUAL CONTROL DEVICE Filed May '7, 1930 March 24, 1931.

N |||||m|m y- @uw Wm (am M www@ Patented Mar. 24, 1931 FFIQCE l THOMAS A. PEEBLES, OF MOUNT LEBANON, PENNSYLVANIA, ASSGNOR TO JOHN M.

HOPWOOD, OFDORMONT', PENNSYLVANIA L DUAL-CONTROL DEVICE Application filed May 7,

This invention relates to fuel feeding, and more particularly to a control system therefor.

In large factories and plants using gas as the principal fuel, it is common to have a large number of boiler furnaces, stoves and other gas lired units supplied from a common gas main. Frequently, the pressure in the gas line decreases to such an extent that the available supply of gas is insufficient for all the units. When such a decrease occurs, it

is desirable to limit the supply of gas to the units of lesser importance; such units of lesser importance may be, for example, the boiler furnaces.

If the boiler furnaces of such a plant have the gas supplied thereto, regulated in accordance with variations in the vboiler steam pressure, it often happens that the boiler dem mands cannot be met without curtailing the supply of gas forthe other' units of the plant. For that reason when the demands of the boiler furnaces are such as to reduce the pressure of gas supply below a predetermined pressure, the control of the gas supply must be taken away from the steam pressure and given over to the gas pressure, in order to allow only such an amount of gas to the boiler furnaces, as will not diminish the supply to other units below a predetermined minimum.

After the gas pressure, by means of the gas pressure regulator, has taken over the control vof the gas supply to the boiler furnaces, and has limited or completely shut off the same, it is necessary (in order to maintain the utility of the boiler furnaces), to supply an auxiliary fuely to such furnaces, until the gas supply and, therefore, `the gas '0 pressure, has been again built up sufficiently to meet the demands of all the gas fired units connected to the common gas main.

` One object of the present invention is to leading to devices whose supply is controlled by steam pressure and limit the amount of gas going thereto when the pressure in said gas line falls below a predetermined value, regardless of the demandsV of steam pressure. Another object of this invention is to proproduce apparatus that will close the gas line 1930. serial 110.450,40?.

duce apparatus that will introduce anauXel illary fuel into those devices when the gas supply therefor has been reduced or completely shut 0E.

A further object of this invention Vis to provide apparatus that will automatically close the auxiliary fuel supply when the pres`- sure in the gas line is again sulhcient to meet the demands on it.

These and other objects which will be apparent to those skilled in this particular art, I attain by means of the apparatus described in the specification and illustrated in the drawings accompanying and forming part of this application.

The drawing is a schematic illustration of an embodiment of this invention as applied to the steam header 1, the gas main 2 and the auxiliary fuel line 3 of a plant adapted to be run by air or gas. A pressure regulator 4 of the type set forth in Hopwood Patent No. 1, 371,243 of March 15, 1921, is connected to the steam header by pipe. Y

VRegulator 4 has a rod 6 connecting it with a fulcrumed lever 7 having an upright arm 8 on one end thereof. The arm 8 has a slot 9 in which the pin 10 of the lever 11 is slidable. The lever 11 is pivoted at one end at 11 to a suitable support and has a weight 12-on its free end. Arod 13 connects lever 11 with the centrally pivoted lever 14 which controls the pivot valve 15 of the metal bellows 16. A pipe 17 connects the metal bellows 16 to the metal bellows 18 of the receiving regulator 19. The receiving regulator 19 has a rod 20 connected to a lever 21 controlling the buttery valve 22 in the gas main 2. f

A secondary regulator 23 of the same general type as regulator 4 is connected to the steam header 1 by the pipe 24. The regulator 23 has a shaft 25V to which is fastened a rod 26 connecting it with the centrally pivoted lever 27 controlling the pilot valve 28of the metal bellows 29. A pipe 30 connects the metal bellows 29 with the metal bellows .31 vof the receiving regulator 32. The receiving regulator 32 has a rod 33 connecting it to the lever 34 to which the butterfly valve 35 of the auX- iliary fuel line 3 is connected. Y

VA pipe 36 leads from the gas main `2 to a balanced regulator 37 of the type described in my copending application Serial No. 370,525, dated J une 13, 1929. The regulator 37 has a rod 38 connecting it with the fulcrumed lever 39 which has an upright arm 40 having a slot 41 in which pin 42 of lever 11, adjacent pin 10 aforesaid, is slidable.

In operation the regulator 4 isV adjusted to open and close at predetermined variations of pressure in the steam header. On a decrease of pressure below the predetermined maximum an impulse will be transmitted through the pipe 5 to the regulator 4 causing it to open. Opening this regulator pulls down the lever 7, by means of the connecting rod 6, disengag ing the pin of the lever 11, from the bottom of slot 9 in arm 8. The support being removed from the pin 10, theweight 12 causes the lever 11 to drop and that end of the centrally piv K oted lever 14 controlling the pilot valve 15 will be raised through its associated connec tion with lever 11. The raising of the lever 14 opens the pilot valve 15 admitting air into the metal bellows 16 increasing the pressure therein. l

For any change of pressure in the bellows 16 th ere is a corresponding change of pressure in communicating bellows 18 through pipe 17. The change of pressure in bellows 18 causes the mechanism associated with the receiving regulator 19 to admit motive fluid, such as compressed air, or oil 4or water under pressure to said regulator causing the rod 20 of the receiving regulator to rise, turning butterfly valve 22 in the gas line toward open position. This opening of the gas' line will admit more gas into vthe boiler to prevent further decrease in the steam pressure.

When there are several fuel consuming uniti connected to the common gas main and the supply of gas available is insufficient to meet all the required demands, it becomes desirable to limit the gas supplygoingto certain less important units, therefore, a balanced regulator is provided and connected with the gas main so that when the gas pressure in Said main drops below a predetermined minimum, the control of the supply will be taken from the steam pressure regulator. Y

For thispurp'ose the balanced regulator 37 is connected to the gas main by a pipe 36.*.

Every change of pressure in the gas main affects the balance in the regulator 37, and to maintain the equilibrium` of said regulator the gas pressure must not fall below a predetermined amount. So long as the pressure is above this amount the balanced float controller 37 would be in one extreme of its travel and would permit free use of gas in accordance with steam pressure. rlhe regulator 37 would not be in equilibrium but would have such a pressure of gas delivered to it that it would be forced to the extreme of its travel.

lllhen this pressure falls to a predetermined Vraising the arm 40 connected thereto.

minimum, the regulator comes into equilibrium and by taking over control of the valvcl 22 and restricting the flow of gas to the boilers, it maintains the predetermined pressure. Thus, a decrease in gas pressure puts thc regulator out of balance, causing it to open, lowering the arm 38, swinging the centrally pivoted lever 39 about its pivot, and thus The pin 42 of lever 11 will engage the bottom of the Vslot 41 and the lever 11 will be raised about its pivot at 11. As the steam pressure will still be dropping, the regulator 4 remains in its open position keeping slotted arm 8 down. rlhe pin lOof lever 11 will, therefore, slide in slot 9. On raising of lever 11, the rod 13 is likewise raised, lowering that end of the centrally pivoted lever 14 controlling the pilot valve 15.

'The pilot valve 15 admits motive fluid to the bellows 16 raising the pressure therein. A like change in pressure will be transmitted through the pipe 17 as before described to the bellows 18, which transmits the change to the receiving regulator 19 and results in regulating the valve 22 in the gas main, thereby limit'ng or completely shutting off the supply of gas going to the boiler furnace regardless of the demands of the steam pressure until trie pressure in the gas main is again built up, putting the regulatorin balance again.

W hen the gas pressure' regulator has thus limited or closed the supply of gas going intok the boiler furnace and the steam pressure is dropping, in order to maintain the elliciency of such consuming unit, itis necessary to introduce an auxiliary fuel into said unit. For this purpose a secondary regulator 23 is provided, that is adjusted to open when the primary regulator 4 is in its open position. As the steam pre3sure drops lower, the regu.- lator 4 finally assumes its open position. The demand of the steam pressure is then communicated through the pipe 24 to the secondary regulator 23, causing it to open, operating the shaft 25 and the rod 26 connected thereto. rlhis causes the centrally pivoted lever 27 to be lowered at one end and raised at the other, the latter opening the' pilot valve 28 which it controls.l The pilot valve admits air to the bellows 29 raising the pressure therein. A corresponding `change in pressure occurs in bellows 31 through the communicating pipe 30.

The change of pressure in bellows 31 causesV the mechanism associated with receiving regulator 32 to admit motive fluid thereto which causes the regulator to open, lower-` ing rod 33, and moving valve 35 toward open position in the auxiliary fuel line 3, admitting fuel so that steam pressure is again built up. l

Vhen the gas pressure in the main is again suilcient to carry the load required of allfthe units connected therewith, the regulator 37 ics will be in equilibrium. On its resuming balanced condition, a change in the associated mechanism above described will take place, causing the arm 40 to be lowered disengaging the pin 42 from the bottom of slot 41 and allowing it to slide therein, giving the control of the fuel supply to the steam pressure regulator 4.

The structure involved in and by pilot valve 15 and metal bellows 16 is that more specifically referred to in my copending application Serial No. 361,657, filed May 9, 1929, for combustion control system, see Figs. 2 and 5 thereof, and in which rod 13 thereof is rod 13 of the instant application.

While various modifications and changes may be made in the system herein disclosed without departing from the spirit and scope of the invention, it is to be understood thatl only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

W'hat I claim as new and desire to secure by Letters Patent is:

1. In a control system regulating the fuel supply to a boiler furnace unit having a steam header, a gas main su plying fuel to said unit and an auxiliary nel supp-ly therefor, the combination of a primary regulator responsive to variations in pressure in the steam header having mechanism attached thereto for controlling a valve in the gas line, a regulator responsive to variations of pressure in the gas main having mechanism for taking the control of said valve away from the primary regulator when the gas pressure drops below a predetermined minimum and a secondary regulator responsive to pressure variations in the steam header adjusted to open when the primary regulator is in an open position and having mechanisml attached thereto for introducing an auxiliary fuel into the boiler furnace unit.

2. The combination in a fuel control system for regulating the supply of fuel to a boiler furnace of means responsive to a decrease in steam pressure for opening a valve in a gas main to increase the supply of gas to said boiler, means responsive to a decrease in pressure in the gas main for closing the valve leading to the boiler, and means responsive to a further decrease of steam pressure for introducing auxiliary fuel to the boiler.

3. The combination in a combustion unit,

of a fuel control system for maintaining aV predetermined steam pressure, comprising a regulator connected with a steam header having mechanism responsive to variations in steam pressure for increasing the amount of gas going into boilers on a decrease of steam pressure, a regulator connected to a gas main having mechanism responsive to variations in gas pressure for closing the gas main when the pressure in said main falls bevalve controlling the opening in said main,

and an auxiliary fuel supply line, provided with a valve regulating the feeding of fuel through said line, means responsive to variations in the steam pressure for operating the valve in said gas main, means responsive to the variations in gas pressure for operating the valve in said gas main and for taking the control of said valve from the mechanism responsive to the steam pressure, and means responsive to a further decrease in steam pressure for actuating the valve in the auxiliary fuel line.

V5. An apparatus for controlling the fuel supply in a combustion unit, comprising a valve in a gas line supplying gas to a consuming unit, a valve in an auxiliary fuel line supplying the same unit, a regulator having mechanism responsive to steam pressure variations for operating the valve in the gas line, a regulator having mechanism-responsive to gas pressure for taking control of said valve when the gas vpressure in said line falls below a predetermined minimum and a regulator having mechanism responsive to a decreased steam pressure `for operating the valve in the auxiliary fuel line when the gas pressure regulator has limited the supply of gas admitted to said unit.

6. The combination in a fuel control system of a regulator connected with a steam pressure line, having mechanism responsive to variations in the steam pressure for operating a valve in the gas fuel line, a regulator connected with the gas line having mechanism responsive to the gas pressure variations for limiting the supply of gas on a decrease of pressure in said line below a predetermined minimum regardless of the demands of the steam pressure regulator, a secondary regulator connected to the steam pressure line having mechanism responsive to steam pressure variations for operating a valve in an auxiliary fuel line and adapted to open said valve when the steam pressure regulator operating the valve in the gas line is in its open position.

7. The combination in a fuel control system of a regulator connected with the steam pressure line, having mechanism responsive to predetermined variations in steam pressure for operating a valve in the gas supply line, a regulator connected with a gas supply line having mechanism responsive to a predetermined minimum gas pressure in 'said line for taking the control of said valve from the steam pressure regulator, and a 'secondary regulator connected to the steam pressure line7 having mechanism responsive to variations in the steam pressure line for operating a valve in an auxiliary Jfuel line, said secondary regulator being adjusted to open When the primary steam pressure regulator is in its open position and the gas pressure regulator has limited the gas supplyl so that it is insuiiieient to maintain the predetermined steam pressure.

Y In testimony whereof, I have hereunto subscribed my name this 5th day of May, 1930.

' THOMAS A. PEEBLES. 

